1. Field of the Invention
The present invention is related to an integrated circuit, and more particularly, to an integrated circuit with a Built-In Self-Test circuit and associated verification method.
2. Description of the Prior Art
In general, a Built-In Self-Test circuit, so called BIST circuit hereinafter, is usually disposed in a chip which needs Read Only Memory (ROM), and this BIST circuit usually can use Single Input Signature Register (SISR) algorithm or Multiple Input Signature Register (MISR) algorithm. The purpose of the BIST circuit is testing product or reading and operating all the data of the ROM to generate a signature pattern when the data of ROM needs to be decided if it is correct and comparing this signature pattern with a predetermined signature pattern to decide if the data stored in ROM has error; wherein the predetermined signature pattern is the signature pattern produced by the BIST circuit when the data of ROM has no error. More specifically, because when the data of ROM has error, it has very high probability to reflect on the signature pattern of the BIST circuit. Therefore, as long as the signature pattern generated by the BIST circuit is the same with the predetermined signature pattern, it can decide the data of the ROM has no error; otherwise, when the signature pattern generated by the BIST circuit and the predetermined signature pattern are different, that means the data of ROM has error.
The above-mentioned predetermined signature pattern will be considered to dispose on chip or off chip according to the consideration of design of designer. In general test of factory mass production, the predetermined signature pattern is disposed off chip, but the predetermined signature pattern is stored in the chip of the electronic product for some electronic products which need to execute BIST when every time turns on (for example, the chip that BIST circuit in). For these electronic products which need to execute BIST when every time turns on, when the internal ROM needs to change the stored signature pattern or other data, it makes the signature pattern generated by the BIST circuit after reading the ROM change as well. Therefore, the predetermined signature pattern stored in the chip needs to be changed correspondingly, so it needs to spend extra costs of mask and also needs extra test for testing if the timing and function of circuit is correct after the design of mask changed.